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Our Personal Equations 




APRIL i, 1885. 

By J. W. HOLLAND, A. M., M. D., 

Prof. Practice of Medicine and Clinical Medicine, University of Louisville. 

[Reprinted from American Practitioner.] 



Our Personal Equations. 

Gentlemen and Ladies: 

In preparing his thoughts for an occasion like this, a speaker 
who has had many predecessors will be lucky if he finds for his 
flail some straw left unbeaten by former threshers. 

That repetition which in the class-room deserves the appella- 
tion "mother of learning," on the rostrum might be condemned 
with the forcible adjective applied by Othello to the iterations 
of Iago. The customary topics of medical orators — Medical 
Education, Expert Testimony, Sanitary Science, Professional 
Ethics — with the phrases staple in such discourses, have been 
worn quite threadbare. 

The most fit for these halls, The Ideal Medical College, is 
one which were better left to some successor more sure of his 
own opinions, and more desirous of bringing the world into 
conformity with them. The old alumnus who has taken a turn 
through the hospital and the laboratories is no longer free to 
doubt that the process of evolution is carrying medical teaching 
through ascending phases. Perhaps, with a conviction in favor 
of a graded curriculum, he is disposed to find fault with the 
annual repetition which, like a circle, makes no progress. If 
so, then his own experience as a student may be appealed to in 
proof that there was a decided advance where it was needed, 
namely, in his own medical knowledge. His second course of 
lectures was to him not the same as his first; it presented to his 
larger intelligence wider reaches than he could at first take in. 

2 Our Personal Equations. 

The circle repeating itself, and so far as the student is concerned 
widening in each cycle by his mental growth, makes the spiral, 
the ideal course of philosophic teachers. As he looks about 
him he can see that the nursing mother moves with her Juno 
stride by sure paths, revealed to eyes that range under level 
brows. Step by step she has walked ahead of us, mending her 
pace as we quickened ours; never out of reach of good movers, 
yet always leading them. Shall we inveigh against the imper- 
fections of our nurture who failed so often to hearken to the 
maternal voice. The 'faults most to be deplored were those in 
ourselves, that we did not use our opportunities better. 

Then we daily sat down to a board of seven courses, and 
nibbled like dyspeptics at the generous fare for which we have 
since hungered. 

Remembering the uniform perversity of mankind, it may 
fairly be questioned if the newly-adopted foster-brothers have 
done much better than we, notwithstanding the epicurean cooks 
who lately sharpened their dull appetites with savory sauces. 
There were great cooks in our day too, who could serve a lec- 
ture in a way to tempt an angel to learn medicine, however use- 
less the art might be in the land without sickness. 

Sitting under a broad porch which gave upon a lawn of that 
blue grass that makes fat cattle and glad harvests, I heard an 
old alumnus discourse of our ahna mater. Said he: "They 
say that a man is thoroughly renewed every seven years. I 
want to go back to 'Old Jeff.' once for each renewal, in the hope 
that the new man will learn better the things new and old than 
did the former man what was taught in his time." He had been 
back once to take draughts from the maternal font, but his busi- 
ness and his babies had since anchored him fast in Kentucky, 
and he consoles himself with the dream that, with other Jeffer- 
sonian angels, in Paradise he may again hear Dunglison tell 
about his experiments on Alexis St. Martin ; Meigs dilate upon 
woman, and her glorious mission of motherhood; Gross lament 
in moving accents the lost art of phlebotomy ; see Biddle wave 
a graceful salute before relating in rhythmic speech the opinions 

Our Personal Equations. 3 

held by Dioscorides concerning the concrete juice of the unripe 
capsule of the Papaver somnifcmm ; and Pancoast go through 
the dextrous motions of operations for which that happy land 
will furnish no clinical material. 

It was a glad reunion, as I sat with that foster-brother that 
June day fifteen years ago and looked out on his waving corn 
and the gold-spotted meadow. I brought him news of the alma 
mater, and set him raking together the embers of old fires, and 
helped him blow them into something of their ancient warmth. 
Would that this occasion were less formal ; that all of us might 
sit as by a family hearth, and each recount in turn the familiar 
things that lose none of their charm by age. We might hear 
some new-born brother tell of things the gray-beard thought 
his own peculiar experience. I am sure that my counterpart 
has sat on these benches since I left them. More than one 
callow youth has come out of the New West to this city of tra- 
ditions, ready to wonder at Independence Hall, and at the 
Franklin Library, founded by the " Junto" of immortal memory. 
More than one, as he took an early pilgrimage to the grave at 
Fifth and Arch streets, has felt that Benjamin Franklin, like 
St. Paul, had been "a citizen of no mean city." More than one 
has had a fresh sense of his own importance as the elder Gross 
indorsed his letter of introduction and consigned it to a pigeon- 
hole with other papers of weighty consideration. More than 
one — aye, thousands — with hearts touched by these small 
amenities from a great man to his insignificant students, have 
proved themselves bound to him with hooks of steel. 

If I hold to my purpose, it is time to stop the flood of rem- 
iniscences that stream in. It were grateful to all of us to cele- 
brate the worthies of our college days and beguile the hour 
with retrospective ramblings. But such an eloquent tribute to 
their memory has been given in this place by one who preceded 
me seven years ago, that the thought of rivalry in this field 
oppresses me, and I turn to another theme for my word-spinning. 
In the half hour for which I feel privileged to hold you by the 
button, there is opportunity to air some reflections about The 

4 Our Personal Equations. 

Personal Equations of medical inquirers. If I succeed in pre- 
senting familiar facts in a new grouping and in such a way as 
not to be disagreeable, then I shall be satisfied. 

The importance of these considerations may not strike every 
one, for scientific inquiry often meets with the reception accorded 
by Confucius to the inquisitive boy. As Carlyle relates it, the 
boy asked Confucius, " How many stars are in the sky ?" The 
sage replied " He minded the things near him." Then said the 
boy, " How many hairs are in your eyebrows ?" Confucius 
answered, " He didn't know and didn't care." 

About ninety years ago the Astronomer Royal of England 
regretfully announced that he had to part with his diligent and 
useful assistant, as he had lately acquired an inveterate habit of 
recording his observations half a second too late. The whirligig 
of time brought the assistant his revenge, as later astronomers 
put just as much reliance on his observations as on those of his 
principal. It was found that both were slightly wrong, both 
were liable to err, as are the most skillful observers. Indeed it 
is only when that various creature, man, is not a part of the 
machinery that we can put entire trust in the register. 

These variations from the absolute truth in measuring minute 
divisions of time and space can be estimated by comparison with 
instruments ot precision, and are usually found to be constant 
for the same person in the same class of observations. The 
habitual error, characteristic of a person, is called his personal 
equation, and is a correction to be applied to his record of all 
events of like nature. Time is an element, first in perceiving, 
next in willing, last in recording. These processes in different 
men go on with varying degrees of rapidity. As quick as 
thought is, there is time in it for some to fall behind others. 
Astronomers tell us that there are variations in researches that 
do not rank as precise which are more marked than those just 
referred to. It is probable that examples of personal equation, 
using the term in its widest sense, are to be found in every form 
of inquiry. As instances of it in observations that do not admit 
of mathematical measurement, we are told of the different pic- 

Our Personal Equations, 5 

tares drawn by different observers of nebulae and the corona of 
solar eclipse. It would be an easy problem for some ophthal- 
mologist to determine if unsuspected and uncorrected astigma- 
tism may not account for some of the variations, as Liebreich 
showed its effects in certain peculiarities of Turner's landscapes. 
While we may not hope to secure an exact valuation of the 
personal equation in such subtile forms as these, it is of impor- 
tance to know when allowance should be made, and in what 
direction to apply efforts for the amelioration of the defect. 

Turning from these distant objects of study, let us follow the 
example of the wise Confucius, and u mind the things that are 
near us." In the science we cultivate there are some occasions 
for micrometric data in physiological research. In every depart- 
ment of medicine it is highly important that observers should 
see, hear, understand, and report accurately, so that others may 
apprehend rightly the appearances of disease and the effects of 

If it were not for the frequent gleams reflected on every 
hand from the spectacles of the young, showing that the enter- 
prising oculist with his trial glasses has been abroad in the land, 
one might think that uncorrected myopia was responsible for 
some errors. Prof. Hermann Cohn states that about sixty per 
cent of the medical graduates at Breslau were short-sighted. 
It is not likely that medical science runs any risk from this 
quarter. Ordinary short-sightedness does not materially affect 
observations made at the bedside, even if the observer should 
be so exceptionally stupid as not to find out his defect during 
his medical studies, or so remiss as not to avail himself of the 
correction afforded by glasses. Besides the sense of form there 
is the wholly distinct sense of color, in which a considerable 
number are unconsciously lacking. For a hundred years Dal- 
tonism has been recognized as a physiological curiosity, but it 
is only a few years since its practical bearings have attracted 
attention of persons long familiar with the importance of the 
errors of vision for form. 

Examination of something like a quarter of a million per- 

6 Our Persona/ Equations. 

sons, in different parts of the world, shows that about four per 
cent of the males in any community may be counted on as rad- 
ically color blind and relatively unfit for occupations requiring 
the use of the color sense. Dr, Jeffries relates an instance of a 
color-blind boy at the Boston Institute of Technology, who 
failed in chemistry, which he had chosen as a profession, be- 
cause without some normal-eyed person by his side he could 
not determine the color of precipitates. 

Apart from this congenital and incurable fault, experts have 
detected a hitherto unsuspected amount of ignorance of colors 
and color names among males of all ages and all degrees of 
education. It shows itself among teachers of physics and even 
among those who have technical uses for the nicest color sense. 
Virchow, at the meeting of the Anthropological Society of 
July, 1878, urged the practical teaching of colors, as he had 
found that the majority of young men were incapable of se- 
lecting with certainty the finer shades of the most common 
colors. In his experience, "It was exceptional that a medical 
student could tell whether a red shaded into a black, blue, or 
brown, or whether a yellow shaded into gray, white, or green.*" 
He continues: "This was a lamentable defect of the eye very 
seldom dependent on color-blindness, but on ignorance of color 
and lack of practice." 

It would not be a wholly fruitless labor if some one with a 
trained and sensitive ear were to take the pitch of certain 
sounds heard in thoracic auscultation, and then test a medical 
class by means of organ pipes to ascertain if these sounds do 
not sometimes pass the limits of hearing in those whose range 
is not of the highest Dr. Wollaston remarked total insensibil- 
ity in some persons to the sound of a small organ pipe, which 
in respect to loudness was far within the ordinary limits of hear- 
ing. There are individuals who have keen ears for the lower 
sounds who never hear the squeak of a bat, the cricket's note, 
or even the chirrup of a sparrow. Sir John Herschel states that 
while some persons not at all deaf can just hear a note four 
octaves above the middle E of the piano, which is below the 

Our Personal Equations. 7 

chirrup of a sparrow, others have a distinct perception of 
sounds two octaves higher. 

It is a reasonable conjecture that some of us present, who 
have normal hearing as respects the middle and lower octaves, 
are defective in the highest without knowing it, and thus fail to 
hear chinking or hissing sounds like the percussion note known 
as the cracked-pot sound and some sibilant rales, fine crepita- 
tion and creaking friction sounds to which others are acutely- 
sensitive. It will be understood that this personal equation 
bears no relation to what is called a "musical ear," which is 
properly defined as a faculty of distinguishing discords. Like 
color-blindness, it has probably an anatomical basis, is congeni- 
tal and not susceptible of improvement. There is, however, 
in those untrained in music a relative inability to discriminate 
in the pitch of sounds of percussion and auscultation like the 
before mentioned ignorance of color shading. In his essay on 
variations of pitch of percussion and auscultatory sounds, Prof. 
Flint -observes that "to the musical ear, more especially if 
skilled in discriminating musical tones, a disparity in pitch 
is more quickly as well as more clearly distinguished." When 
the beginner finds a difficulty in perceiving a difference in 
sounds apparent to the practical diagnostician, Prof. Flint has 
made it manifest by requesting him to compare the two sounds 
as if they were musical notes, with reference to pitch. If he 
has had musical cultivation, the disparity is quickly perceived. 
Such a preliminary training has been found of material service 
in acquiring expertness in auscultation and percussion. 

In an article in the Fortnightly Review, based upon a large 
amount of testimony and controlled by the methods in use by 
statisticians, Mr. Francis Galton states that he finds great differ- 
ences in the power of forming pictures of objects in the mind's 
eye. This power of sight-memory is a reversal of the order ot 
events in the original perception. An excitement of the brain 
propagates itself outward to the visual center back of the retina, 
producing pictorial irritations more or less true or vivid, accord- 
ing to the vigor of the outward impulse. 

8 Our Personal Equations. 

In some this faculty is habitually weak, and the propagation 
will take place only under such peculiar states as dreams, delir- 
ium, great excitement, or stimulation by drugs. Others repro- 
duce past scenes with a distinctness little short of actual sight. 
It was found that the medium quality of mental imagery, though 
fairly vivid, was incomplete. Only one in sixteen had it in the 
degree to be desired. 

I venture the opinion that this faculty of mental imagery is 
the basis of that knowledge of topographic anatomy of so great 
importance to the operator especially, but valuable to the doctor 
at every turn. Upon it, to a great extent, depends the student's 
ability to state the relations of nerve, artery, and vein, without 
resorting to the mnemonic arrangements of N., A., and V., that 
quiz-masters cram them with. This natural gift, when joined 
to certain other qualities — self-reliance and mechanical tact — is 
the making of a surgeon. I have known a man of fine mind, 
well equipped in these last-named respects, and who had good 
opportunities for advancement, fail as an operator of the first 
rank because he lacked this power of visual memory. It is not 
rare for the surgeon, on the eve of an operation, to refresh the 
pictures memory drew in fading colors by resort overnight to 
the anatomical atlas. This serves the purpose in many cases, 
but it is not the best way of knowing the anatomy of a surgical 

According to Napoleon, the rarest and most valuable trait 
in a soldier is "two-o'clock-in-the-morning courage." So, I 
would say, the ideal anatomist is one who, awakened at mid- 
night for an emergency, has his knowledge at his fingers' ends. 

It is the opinion of Galton that in twelve out of sixteen this 
topographic memory may be developed to a useful degree by 
education. He lays especial stress upon the testimony of the 
Director of the National School of Design in Paris, who, begin- 
ning with the simplest figures, trained his pupils to study mod- 
els with the view of drawing them from memory. After four 
months' practice they had no difficulty in summoning images 
at will, holding them steadily in the mind, and drawing them 

Our Personal Equations, 9 

with accuracy. He relates the experience of an engineer, who, 
after a few weeks of systematic practice, found, to his delight, 
that he had become an adept at color-memory, which, up to 
that time, had been an undeveloped faculty. Mechanicians, 
engineers, and architects, who practice the drawing of an in- 
tended structure in all its dimensions, usually have mental vision 
of remarkable clearness and precision. This faculty must have 
been possessed by the late Prof. Wallace in an unusual degree. 
By off-hand modeling with colored clays he would give plastic 
expression to his picture-memory of anatomical details. Doubt- 
less there are many here who remember how, with a few deft 
touches, he would make tumors rise before the class, or would 
inflict on counterfeit pelvic viscera all sorts of pathological 

In the presence of older and better teachers than myself, it 
is with diffidence that I hazard the suggestion that a course of 
practical anatomy, in which the student would be required to 
draw in outline from memory, or roughly work up in clay, the 
forms and relations of parts laid bare in his dissections the day 
before, would be a valuable addition to the present means of 

Conning of text-books on anatomy gives verbal memory; 
but, according to Galton, bookish methods tend to repress the 
pictorial gift of nature. It is possible to starve it by disuse, 
and again to feed it by judicious methods of education. There 
are many present, fresh from the quiz-room, who can give, by 
an effort of verbal memory, the layers of structure encountered 
in making the dissection for inguinal hernia, who can not make 
a sharp picture of them in their minds, much less an outline 
drawing of the relations of the inguinal rings and other parts 
concerned. If each of ten doctors, taken at random, were to 
describe faithfully the mental vision he would have of the path 
of a bullet shot through a given spot in the trunk of a subject, 
I warrant there would be evidence of personal equation as well 
as of imperfect modes of instruction. It may be objected that 
the proposed improvement in the conventional method requires 

IO Our Pergonal Equations. 

that the student should have an unusual talent for drawing. To 
make an outline indicating the form and relative position of 
parts does not call for any artistic power worth the name. Ex- 
perienced teachers assert that any one not blind, lame in the 
hand, or imbecile, can acquire at least this degree of proficiency. 
It is within the reach of any one who can learn the art of pen- 
manship. In educational conventions one hears a good deal 
said about the Nezv Education. Its advocates claim for it that it 
is the cream of traditional methods worked into a system. It 
is wholly different from the Chinese plan of committing to mem- 
ory endless pages from Confucius, and thus loading the mind 
with good-for-nothing lore. Its primary aim is avowed to be 
to teach the pupil to see, hear, and understand correctly, in 
order that he may take up the study and work of after-life as 
free from defects of his five senses as culture can make him. 
Practice in drawing is a salient feature. It has been found that 
along with the training of the hand, this tends to develop quick- 
ness and accuracy of perception, and a fidelity in objective 
memory that is surprising to those educated under the old 
routine. Courses in music have been for years an element in 
the public school curriculum in many parts of our country, 
with results equally gratifying. While it has not been expected 
that any one can be made to hear notes beyond his normal 
scale, improvement in the power to discriminate the pitch of 
sounds has been unequivocal. You and I may consider our- 
selves too old to go into training of this sort; but in this we 
differ from a busy practitioner over sixty years of age, a neigh- 
bor of mine, who, in a recent affliction, found solace and sub- 
stantial self-culture in taking up a course of drawing. We can 
at least see to it that our own children and the students we send 
up to alma mat l er in the twentieth century have not only a good 
academic education, but, better than that, have been taught with 
especial reference to seeing, hearing, and understanding cor- 
rectly whatsoever things come up in the life-work before them. 
It is a popular impression that when one brings to the aid of 
the lens in his eye other lenses outside, the chances of fallacy 

Our Personal Equations, 1 1 

are thereby removed. That this is erroneous all working 
microscopists are well aware. There is a distinguished histol- 
ogist in New York who teaches and demonstrates to the appar- 
ent satisfaction of his pupils that there is a reticulum in the 
blood corpuscle which is an exhibition of the network present 
generally in protoplasmic structures. On the other hand, the 
great majority of our histologists and the most skilled manipu- 
lators of high power objectives assert their inability to see the 
network spoken of. What they see in his demonstration is, 
according to them, the usual appearance presented by granular 
bodies when viewed slightly out of focus. If the drawings made 
by him represent the cell as he sees it, there is a decided 
difference between his microscopic vision and that of most 
experienced observers. This would be an instance of personal 
equation on the part of some one. As to the party to whose 
observations a factor of error must be applied, photography 
alone offers a final judgment. By this means the late Dr. Wood- 
ward succeeded in convincing foreign microscopists that the 
resolution of Nobert's 19th band was not simply a matter of 
faith but one of sight. 

It may turn out that the difference is not one of sight but 
one of interpretation. The liability to misinterpret besets the 
path of the scientific observer in every field. 

When Carlyle said that " a man sees what he brings with him 
the power to see," he meant that through the optical apparatus 
of vision there was an eye of the intellect looking, perceiving, 
and interpreting. This recipient eye back in the optic lobes or 
perhaps in the visual center of the cortex, colors every object of 
sensation whose image passes into it. 

The mind is conscious of that object, not as it entered but as 
it has been refracted by the prismatic medium of personality 
through which it was transmitted. A great obstacle in the way 
of seeing things plainly as they are, is a prepossession in favor 
of a certain view of them. Pride of opinion may thus create a 
personal equation ; so may a love of sensation or a rage for 
novelty ; so may the fanaticism of hypothesis. To a pet 

1 2 Our Personal Equations. 

hypothesis has been ascribed the quality of assimilating all 
observations to itself. Standing erect among the facts it is a 
convenient stem around which the investigator twines his pliant 
impressions, stem and vine, each helping to hold the other up. 
It is not my intention to say aught in dispraise of theory as 
such. It has been well said that nothing is so helpful to the 
investigator as a good theory. Like wine it is a good servant 
but a bad master. Used rightly it is a wholesome stimulant, 
but some thirsty souls are so constituted that they can not take 
it in moderation. If they once take a sip at a theory they tope 
with it, and under its influence see things double and lose their 
mental equipoise, until time and the jostling of critics sobers 
them off. 

It has been recently announced that the new American 
Society for Psychical Research disclaims that its object is the 
study of supernatural phenomena. The ground they propose 
to tread is tolerably safe so long as they confine their inquiry to 
those mental states in which certain persons, called " thought 
readers," seem to have the faculty of knowing some of the ideas 
of others. If we may judge by the career of the English 
society of that name, there is a tendency in those who concern 
themselves about " thought transference M to step over into the 
twilight land of clairvoyance where the marsh meteors soon lead 
them into a bog. The large proportion of physicians in the 
American Society is an assurance that it will not be allowed to 
degenerate, as did the English one, into a medium for giving 
consequence and permanence to all the ghost-stories treasured 
in bereaved families as assuring glimpses of the presence of 
their dead. 

Doubtless " there are more things in heaven and earth than 
are dreamt of in our philosophy," but when an observer's 
feelings are strongly interested they so influence his judgment 
as to what he sees of these undreamt of things, as to make 
him a very unreliable witness. It would be difficult to exagger 
ate the tendency to self-deception in examining the phenomena 
of spiritualism when the investigator is possessed with a long- 

Our Personal Equations. 1 3 

ing for evidence of the spiritual existence of some dead friend 
or relation. 

Only those rare beings who can get outside of themselves, 
who are able to put aside the craving for communication with 
the dear travelers in that undiscovered country, only these are 
qualified to estimate with judicial fairness the extravagant pre- 
tensions of clairvoyance, spiritualism and mesmerism. These are 
mentioned together because opinions, like other furniture, " go 
in sets;" and it is in these that the dominant idea referred to 
becomes a personal equation of notable size. It is a matter for 
medical men to consider, inasmuch as it is vaunted that those 
who believe in and resort to these occult powers, have great ad- 
vantages in diagnosing and curing disease. It is alleged that 
some persons possess by nature a faculty of seeing through 
opaque objects ; they are clairvoyant, see by transcendent vision 
things out of the common range. A patient of mine dropped 
in with a friend at the residence of one of these "psychometric 
mediums," who nearly frightened her out of her wits by gravely 
telling her that he could see that she suffered from headache 
and pain in the side, due plainly to the fact that her liver was 
bound back to her diaphragm. She thought it witchcraft that he 
should without examination divine these things, but was some- 
what reassured when told by me that as for the headache and 
sideache, they might be counted on as symptoms in almost 
every woman that entered a doctor's office, and that she would 
be in a bad way if her liver was not so anchored. I have never 
seen or heard on good authority of one of these gifted beings 
that had the powers of diagnosis possessed by a new medical 
graduate, and yet belief in the verity of their claims has grown 
by waves of popular excitement until it includes people of un- 
doubted intelligence. At times the epidemic has seized men of 
science and even educated physicians, though the vast majority 
of the well instructed look on clairvoyance as unprofitable in 
speculation and quackery in practice. 

In the library on Fifth Street, founded by Franklin and his 
"Junto/* is a copy of a report on Animal Magnetism, made by 

14 Our Personal Equations. 

Dr. Franklin and others to the French Academy just one hun- 
dred years ago. Like all documents that Franklin had a hand 
in making, it is thorough and perspicuous. The experiments 
by which they were convinced of the baselessness of Mesmer's 
claims are models of ingenuity. They show the master mind of 
that wonderful Philadelphian, who had a seeing eye of the 
highest power. Did you ever think how much his vision re- 
sembled the spectacles he invented. Half the glass was for 
near and half for distant objects. Nothing that interested him, 
either remote or at hand, was he content to view dimly. Upon 
them all, smoking chimneys and thunderbolts, he directed his 
clear and true sight. The pretensions of Mesmer alike with 
the pretentions of tyrants he saw through and exhibited to the 
gaze of all. At the same time in his report he concedes a cer- 
tain value to the phenomena exhibited by those said to be mes- 
merized, they furnish " important evidence of the power of the 

Again and again did the French Academy respond to the 
popular clamor for investigation, until it dismissed the subject 
of clairvoyance in a report published in 1837, by stating that 
the facts furnished have nothing in common with physiology or 
therapeutics. A standing offer was made by Burdin, and since 
repeated by others, of large sums of money to any one who 
should produce a clairvoyant able to read through an opaque 
medium. Although the experiment has been variously altered 
at the instance of those making the trial, no one has yet suc- 
ceeded in winning the prize. The attempts have, however, re- 
sulted in the detection of the means by which the credulous have 
at times been imposed on. When the neurologists of the Society 
for Psychical Research shall discover an individual who can sat- 
isfy this reasonable demand, it will be conceded that in this 
direction their labors have not been in vain. Experience forbids 
us to hope than such a one exists. 

For fifty years, those claiming to see blindfold what is not 
revealed to the eye, have not brought to human knowledge a 
single new fact concerning the inner workings of things. What 

Our Personal Equations. 1 5 

discoveries in physiology and pathology would flow from the 
use of any instrument that would compensate, even in a small 
degree, for the limitations of sight and hearing! So often 
baffled and led astray by the inadequacy of the eye and ear, 
mankind would then have to make allowance for a personal 
equation in doctors who attempted to solve medical enigmas 
without its aid. 

Alas ! for the beautiful dream, no clairvoyants have ever pen- 
etrated this veil further than common people; indeed they have 
left the glorious privilege of adding to the sum of scientific 
knowledge entirely to folk of five senses only, while they grope 
on in a limbo where honest minds seem forever doomed to 
struggle with fraud, credulity, and superstition. 

If the Society for Eiy*i€al Research shall make a report differ- 
ing in important particulars from the settled coviction of most 
men of science, again, as often before, will be raised the charge 
of "bias and credulity," and again will be heard the retort of 
"scientific prejudice and intolerance." 

Between these two extremes it will be hard to find and hold 
the diagonal line. In such a controversy we shall be much in 
want of a mental dynamometer, which shall give us some 
approximation to the personal equation of mental strength in 
the disputants. 

All the traditional methods of gauging the mind depend too 
much on tests of memory, quite a subordinate faculty. It does 
not seem at all likely that man shall ever invent any edequate 
plummet to sound these "abysmal deeps of personality." Nor 
can he ever be satisfied to turn away from this question as Con- 
fucius did from that concerning the number of hairs in the eye- 
brow, and say because he does not know how much allowance 
to make for personality, therefore, he will not care for it as a 
factor in medical investigation. 

Of one thing we may be sure, that, in cultivating our five 
senses, much may be done to lower all their personal equations. 
While thus engaged there can be no doubt that we walk on solid 
ground and in the middle of the road. Instead of forming mag- 

1 6 Our Personal Equations. 

netic circles in the dark, waiting in a pliant hour for spiritual 
insight to develop to the point of receiving impressions concern- 
ing things which shun the light of day, the sure way will be 
by incessant practice to sharpen the natural powers of observ- 
ation so as to acquire that professional sagacity which notes 
myriads of fine differences and resemblances that escape the 
scrutiny of the untrained intellect. May ours be that clear- 
sighted skepticism that would discount every personal equation 
in ourselves and others; that would turn the white light of crit- 
icism upon every reputed revelation lest some fallacy steal in 
under the garb of truth. To free itself from bias and achieve 
perfect uprightness, the scientific mind must be imbued with a 
religion in which 'slight adoration shall be offered to those 
natural laws that have been called the thoughts of God; in 
.which the best faith shall be honest doubt, the worst unbelief 
shall be to question the permanence and beneficence of truth, and 
in which a grievous sin shall be imputed to him who is indif- 
ferent to its pursuit. Should it ever want a litany, what better 
invocation than: 

"Give me no light, great Heaven, but such as turns 
To energy of human fellowship; 
No powers, save the growing heritage 
That makes completer manhood."